This invention relates in general to a so-called flash mechanism for use with cameras, which permits automatic proper diaphragm settings to be achieved in the mechanism linkage with the rotation of a distance ring in flash photography utilizing flash lamps or the like, and more particularly involves a flash mechanism having an exposure correction member.
Various types of flash mechanism for use with cameras have been known and some of them are used in practice.
In cameras having flash mechanisms which permit automatic proper diaphragm settings in accordance with the setting of a distance ring, the types of flash mechanism can be classified as follows:
(1) THE TYPE HAVING AN EXPOSURE CORRECTION MEMBER, SUCH AS A CORRECTION ELEMENT FOR THE GUIDE MEMBERS OF AN ILLUMINATION DEVICE OR A CORRECTION ELEMENT FOR FILM SENSITIVITY; OR
(2) THE TYPE HAVING NO SUCH EXPOSURE CORRECTION MEMBER; AND
(3) THE SO-CALLED PROGRAM SHUTTER TYPE WHICH HAS MEANS THAT SERVE BOTH AS DIAPHRAGM BLADES AND SHUTTER BLADES; OR
(4) THE ORDINARY SHUTTER TYPE HAVING DIAPHRAGM BLADES AND SHUTTER BLADES SEPARATELY.
Thus, a particular camera may incorporate either of types (1) or (2) with either of types (3) or (4).
With respect to the flash mechanism having an exposure correction member, it can be classified into two subtypes depending upon whether the member works electrically or mechanically.
The flash mechanism of the present invention is of the type having a mechanical exposure correction member and is applicable to simple and inexpensive cameras.
Several kinds of flash mechanism belonging to the type of the present invention have been known.
However, in the conventional mechanism of this type, the linkage relations are very complex and there are many contacting portions of pins and cam surfaces. Thus, it is inevitably subject to high production cost.
Moreover, in the conventional mechanism, since the stretches of component members in the direction of the optical axis and also in the direction normal to the optical axis are great, a large housing space is necessary. In addition, the frictional resistances are great and accordingly the operation is apt to become unsmooth.